Role of PHF6 in Normal Hematopoiesis and hematopoietic stem cell biology

PHF6 在正常造血和造血干细胞生物学中的作用

• 批准号: 10063768
• 负责人: Feng-Chun Yang
• 金额: $ 30.7万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-15 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10063768
• 关键词: Role; PHF6; Normal; Hematopoiesis; hematopoietic

The plant homeodomain finger 6 (PHF6) is a member of the plant homeodomain (PHD)-like finger family genes. PHF6 is frequently mutated in T-cell acute lymphoblastic leukemia (T-ALL, ~15%) and various myeloid malignancies including acute myeloid leukemia (AML, ~3%), myelodysplastic syndrome (MDS, ~3%) and chronic myelomonocytic leukemia (CMML, ~5%). Interestingly, the PHF6 genetic lesions in hematological malignancies are largely frameshift and nonsense mutations distributed throughout the gene, indicating that these PHF6 mutations likely result in the loss of WT PHF6 and the expression of a truncated PHF6. Furthermore, clinical studies showed that PHF6 mutations confer worse overall survival in patients with MDS and AML. Despite the clinical significance of PHF6 mutations in hematologic neoplasms, the role of PHF6 in normal hematopoiesis and the impact of its mutations on the hematopoietic stem/progenitor cell (HSPC) functions remain unknown. In addition, it is not known whether the truncated-PHF6 leads to a bona fide loss-of- function or exerts a gain-of-function in hematopoiesis. Given the fact that PHF6 is located on the X chromosome and its mutations are male dominant, we hypothesize that the PHF6 mutations confer a gain-of- function in vivo. We therefore generated a conditional Phf6 knock-out (Phf6flox) mouse model to determine the role of PHF6 in normal hematopoiesis and whether loss of Phf6 affect HSPC cell fate and functions. In addition, we also established two transgenic mice expressing two different patient-derived truncated PHF6 (Phf6R274X and Phf6R342XTg) solely in hematopoiesis to determine the impact of truncated PHF6 on HSPC activities. Our preliminary data showed that Phf6-loss in mice increase hematopoietic stem cell self-renewal, indicating that PHF6 plays an important role in HSC regulation. We also found that PHF6 truncation expression confer a gain-of-function to promote HSC self-renewal. With these models in hand, we will determine the hematological phenotypes of mice with combined Phf6-inactivation and expression of truncated PHF6 in hematopoiesis, and define the cellular and molecular mechanisms by which PHF6 and its truncated mutations impact on HSPC functions. Mechanistically, we will identify key PHF6 and truncated PHF6 binding partners and determine the importance of these interactions to their genomic localization and common target gene expression in HSPCs. These studies will greatly improve our understanding for the role of PHF6 in normal hematopoiesis as well as the impact of PHF6 mutations on HSPC functions. Moreover, these PHF6 mutant models offer a biological platform in which drugs can be tested and developed. These studies are timely and fundamentally important for advancing our knowledge on PHF6 in normal hematopoiesis and HSPC biology.

植物同源结构域指 6 (PHF6) 是植物同源结构域 (PHD) 样指家族基因的成员。 PHF6 在 T 细胞急性淋巴细胞白血病 (T-ALL，~15%) 和各种骨髓细胞白血病中经常发生突变 恶性肿瘤，包括急性髓系白血病（AML，约 3%）、骨髓增生异常综合征（MDS，约 3%）和 慢性粒单核细胞白血病（CMML，~5%）。有趣的是，PHF6 基因在血液学中的损伤 恶性肿瘤主要是分布在整个基因中的移码和无义突变，这表明 这些 PHF6 突变可能导致 WT PHF6 的丢失和截短的 PHF6 的表达。 此外，临床研究表明 PHF6 突变导致 MDS 患者的总生存期较差 和反洗钱。尽管 PHF6 突变在血液肿瘤中具有临床意义，但 PHF6 在血液肿瘤中的作用 正常造血及其突变对造血干/祖细胞 (HSPC) 的影响 功能仍未知。此外，尚不清楚截短的-PHF6是否会导致真正的损失- 在造血功能中发挥功能或发挥功能获得性。鉴于 PHF6 位于 X 上 染色体及其突变是男性显性的，我们假设 PHF6 突变赋予了增益- 在体内发挥作用。因此，我们生成了条件 Phf6 敲除 (Phf6flox) 小鼠模型来确定 PHF6 在正常造血中的作用以及 Phf6 的缺失是否会影响 HSPC 细胞的命运和功能。在 此外，我们还建立了两只转基因小鼠，表达两种不同的患者来源的截短PHF6 （Phf6R274X 和 Phf6R342XTg）仅在造血作用中确定截短的 PHF6 对 HSPC 的影响 活动。我们的初步数据表明，小鼠 Phf6 缺失会增加造血干细胞的自我更新， 表明PHF6在HSC调节中发挥着重要作用。我们还发现PHF6截短表达 赋予功能获得以促进 HSC 自我更新。有了这些模型，我们将确定 Phf6 失活和截短 PHF6 表达相结合的小鼠的血液学表型 造血作用，并定义 PHF6 及其截短突变的细胞和分子机制 对 HSPC 功能的影响。从机制上讲，我们将识别关键的 PHF6 和截短的 PHF6 结合伴侣 并确定这些相互作用对其基因组定位和共同靶基因的重要性 HSPC 中的表达。这些研究将极大地提高我们对PHF6在正常情况下的作用的理解。 造血作用以及 PHF6 突变对 HSPC 功能的影响。此外，这些PHF6突变体 模型提供了一个可以测试和开发药物的生物平台。这些研究是及时且有效的 对于增进我们对正常造血和 HSPC 生物学中 PHF6 的了解至关重要。